1. Field of the Invention
The present invention is related to a method for fixing metal onto a surface of a substrate, and particularly related to a method for fixing metal onto a surface of a substrate by means of a mercaptoalkylsilatrane compound.
2. Description of the Related Art
Due to progress and convenience of biomedical detection technologies, the technology of using biomedical sensors to perform biological detection has gradually become the major approach of the detection of various diseases in recent years. To increase the sensitivity of biological detections, surface modifications are performed on various substrates such as metal, plastic, silica, or others to facilitate the fixing of recognition molecules or sensing materials on the surface of the substrates.
Among all the methods of surface modification, the more common are the following two: the first one is to use phosphate compounds to perform surface modification, and the other one is to use silicon compounds to perform surface modification to form a self-assembled layer. Among the methods of using silicon compounds to perform surface modification, two popular series of compounds are alkyl-SiCl3 or alkyl-Si(OR)3, where OR is an alkoxy group. To perform surface modification, upon the hydrolysis of alkyl-SiCl3 or alkyl-Si(OR)3 to form silanol group(s), their major reaction is the condensation of a hydroxyl group of the substrate with a silanol group of the silicon compound to form a Si—O—Si bond. No matter the chlorine (Cl) or the alkoxy group of the aforementioned bifunctional linker compounds, however, both are difficult to effectively control and utilize owing to their sensitivity to moisture which leads to agglomeration and polymerization on a substrate during deposition, generally resulting in multilayer deposition and irregular surface morphology, and thus require stringent application conditions.
Besides, noble metal nanoparticles are often used as sensing materials. For the immobilization of noble metal nanoparticles on substrates, a silane compound having an amino group (NH2) is commonly utilized to immobilize noble metal nanoparticles via electrostatic attraction force, for example the surface modification of using (3-aminopropyl)trimethoxysilane (APTMS). However, as compared to the surface modification method of using the mercapto group based on covalent bonding, the immobilization method with the amino group with noble metal nanoparticles via the electrostatic attraction force is weaker, and thus imposes limitations on the applications of fixing noble metal nanoparticles on a substrate.